Exploring Spatio-Temporal Trends in Heavy Metal Concentrations: A Study of Water, Sediment, and Selected Fish Species in Shiroro Lake, Niger State, Nigeria. Abstract:
Water quality parameters were measured, and the results indicated dissolved oxygen levels ranging from 2.20 to 4.10 mg/L, temperature between 26.60 to 30.20 oC, biological oxygen demand from 1.20 to 3.00 mg/L, conductivity from 49 to 120 µS/cm, alkalinity from 18 to 36 mg/L, phosphate from 0.16 to 2.28 mg/L, sodium from 7.56 to 14.00 mg/L, pH from 6.56 to 7.96, total dissolved solids from 75 to 99 mg/L, total hardness from 30 to 48 mg/L, and potassium from 1.16 to 2.42 mg/L.
The concentration of heavy metals in sediment samples collected from the three stations varied, with zinc ranging from 0.095 to 0.25 mg/L, copper from 0.015 to 0.905 mg/L, lead from 0.00 to 0.15 mg/L, chromium from 0 to 0.03 mg/L, and cadmium from 0 to 0.015 mg/L. For water samples collected from the same stations, the heavy metal concentrations were as follows: zinc ranged from 0.01 to 0.18 mg/L, copper from 0.01 to 0.165 mg/L, lead from 0 to 0.2 mg/L, chromium from 0.00 to 0.01 mg/L, and cadmium from 0 to 0.01 mg/L. Notably, the concentration of cadmium in the water exceeded the toxicity threshold set by the World Health Organization (WHO) for drinking water.
In the analyzed fish samples, higher levels of zinc (1.47 ± 0.50 mg/g) and copper (0.73 ± 0.31 mg/g) were observed compared to other heavy metals. However, all heavy metal concentrations in fish were found to be within WHO’s maximum permissible limits. The potential ecological risk index (PERI) mean values for all stations indicated slight ecological risk, with Zn 0.083, Cu 0.29, Pb 2.06, Cr 0.03, and Cd 0.48. The geo-accumulation index mean values for the five heavy metals (Zn -2.42, Cu -2.06, Pb -1.56, Cr -0.92, and Cd -0.75) indicated an unpolluted state at the sampling stations. Furthermore, the enrichment factor (EF) values were all below one (<1), indicating a crustal enrichment origin at the sampling stations.
Based on the physicochemical parameters measured, the overall pollution level in Shiroro Lake was found to be low, as all water quality parameters were either slightly below or within the WHO’s permissible limits. However, it is crucial to note that the water in Shiroro Lake is not safe for human consumption due to the potential risk of Cd exposure.
Exploring Spatio-Temporal Trends in Heavy Metal Concentrations: A Study of Water, Sediment, and Selected Fish Species in Shiroro Lake, Niger State, Nigeria.